1. Field of the Invention
The present invention relates to the LCD device technical field and, more particularly, to a method for improving the EMI performance of an LCD device.
2. Description of Related Art
In general, since the transistor transistor logic (TTL) interface, located between the timing controller and the source drivers of an LCD device, requires a lot of data buses to transmit image data, a serious electric power consumption and a severe Electro-Magnetic Interfering (EMI) performance are experienced at the TTL interface.
FIG. 1 is a block diagram showing the conventional timing controller having a TTL transmission interface. In order to improve the power consumption and the EMI problem occurring between the timing controller 1 and the source driver, the timing controller shown in FIG. 1 employs a Dual Port transmission method to transmit the image data to the source drivers. If the resolution of the display gray level is 8 bits, then 48 data bus lines are required (8 bit×3 RGB×2 Dual port=48). Besides, for corresponding with the two sets of input LVDS signal, the output terminal of the timing controller 1 further comprises two data bus lines, i.e. the EDTA [47:0] and ODTA [47:0].
FIG. 2 is a block diagram showing the conventional timing controller having a PPTTL transmission interface, which can solve the problem of too many data bus lines shown in FIG. 1. In FIG. 2, the timing controller 2 employs a Point-to-Point transmission method to transmit the image data to the source drivers. If the display panel module uses 10 source drivers, then only 30 data bus lines are required (10 source driver ICs×3 RGB=30). Moreover, by employing the Point-to-Point transmission method, the number of the data bus lines required is no longer related to the resolution of the display gray level (6 bits or 8 bits). Therefore, in display system having higher resolution, the advantage of the Point-to-Point transmission method, relative to the Dual Port transmission method, is more obvious. Nevertheless, for a large-sized display panel, the distortion of the image data, caused by the PPTTL interface employed the Point-to-Point transmission method is more significant.
FIG. 3 is a schematic view showing the conventional panel module employing the dual port transmission method. In FIG. 3, the display panel 3 is divided into a first display portion 31 and a second display portion 32. The timing controller (not shown) transmits the image data to the source drivers (not shown) by employing the dual port transmission method. The source drivers (not shown) then transmit the image data to the first display portion 31 and the second display portion 32 (i.e. two-way transmission), respectively. Therefore, by lowering the CLK signal operating frequency, the electric power consumption and the EMI performance can be improved.
FIG. 4 is a timing diagram of the conventional dual port transmission method. In FIG. 4, the dual port transmission method using a CLK signal to control the transmission of two image data, i.e. the first sampling waveform controls the transmission of the image data A and the image data B. As a result, by employing the dual port transmission method, the number of the CLK signals required for displaying image can be reduced by half. However, as the size of the display panels gets bigger and bigger, and as the resolution of the display panels have increased significantly, the number of the CLK signals has also increased a lot. As a result, even by employing the dual port transmission method, the electric power consumption and the EMI performance still cannot be improved.
Therefore, it is desirable to provide a method for improving the EMI performance of an LCD device to mitigate and/or obviate the aforementioned problems.